1. Field of the Invention
The present invention relates to an antenna, more particularly to a dual-band antenna.
2. Description of the Related Art
Currently, there are many different wireless telecommunication technologies. Depending on the coverage, the technologies can be categorized into different categories of network. A network employing a technology that provides city-to-city or even country-to-country coverage is referred to as a Wireless Wide Area Network (WWAN), which typically operates at frequencies ranging from 824 MHz to 960 MHz and from 1710 MHz to 2170 MHz. A network employing a technology that provides a coverage with a radius of approximately 100 meters from an access point to a subscriber is referred to as a Wireless Local Area Network (WLAN), which typically operates at frequencies ranging from 2412 MHz to 2462 MHz (820.11b/g) and 4900 MHz to 5875 MHz (802.11a).
Referring to FIG. 1, portable computers (e.g., laptop computers, notebook computers, network computers) and handheld devices are generally provided with a conventional planar inverted-F antenna 9 for access to a WWAN. Nevertheless, the planar inverted-F antenna 9 is known to have a narrow bandwidth, low efficiency, and a directional antenna radiation pattern.